1. Field of the Invention
This invention relates to a thermal storage device which interacts with a circulating coolant in an air conditioning system, and more particularly to an ice thermal storage device including a hollow ball containing a liquid and an elongated weight member connected to a ball-shaped flexible air pocket which keeps said air pocket in the geometrical center of the hollow ball.
2. Description of the Related Art
For air conditioning systems that operate only by day, water recirculated and cooled over ice offers an economical means for space cooling. Cold water is pumped from a reservoir having a plurality of thermal storage containers which contains ice. In such an air conditioning system, excess electric power at night is used to cool the recirculating brine, thereby freezing the water in the thermal storage balls to ice by a heat transfer process. The ice in the thermal storage containers chills the recirculating brine. This chilled recirculating brine is used for air cooling purposes by day during which time electric power may be insufficient. This concept may shift the electric load from peak to off-peak to level the power demand. We named it as "Ice Thermal Storage Air Condition".
In the past, to prevent the thermal storage containers from being deformed by the expansion of ice, many types of thermal storage containers have been developed. One type of a thermal storage container is a casing formed with pleated walls. However, the uneven surface of the pleated walls of the container increases the friction force between the recirculating brine and the container, thereby increasing the power consumption.
Referring to FIG. 1, an improved conventional thermal storage ball 10 includes a ball-shaped flexible air pocket 12 and a liquid 11 which is contained therein to be frozen. The thermal storage ball has a smooth surface which can reduce the friction force between the recirculating brine and the ball. A plurality of ribs 13 are connected to the air pocket 12 and extend to the internal face of the ball 10 in order to keep the air pocket in the center of the thermal storage ball 10 where the liquid 11 is gradually frozen. The air pocket 12 contorts inwardly and uniformly to prevent the deformation of the thermal storage ball 10 when the liquid 11 is frozen and expends in volume. However, since the thermal storage ball 10, the air pocket and the ribs 13 are usually made of light plastic materials for the ease of manufacturing, the thermal storage ball 10 will submerge partially into the recirculating brine. Unfortunately, this will reduce the heat transfer efficiency between the circulating brine and the liquid 11 contained in the thermal storage balls 10. In addition, the mounting of many ribs 13 to the air pocket 12 in order to keep the air pocket 12 in the center of the thermal storage ball 10 during the heat transfer process is troublesome and not cost-effective.